Control method for a direct injection system of the common-rail type provided with a shut-off valve for controlling the flow of a high-pressure fuel pump

摘要

A control method of a direct injection system (1) of the common-rail type provided with a shut-off valve (24) for controlling the flow rate of a high-pressure fuel pump (6); the control method contemplates the steps of: feeding the pressurized fuel to a common rail (5) by means of a high-pressure pump (6) which receives the fuel through a shut-off valve (24); cyclically controlling the opening and closing of the shut-off valve (24) for choking the flow rate of fuel taken in by the high-pressure pump (6); adjusting the flow rate of fuel taken in by the high-pressure pump (6) by varying the ratio between the duration of the opening time and the duration of the closing time of the shut-off valve (24); determining a lower limit value of the opening time of the shut-off valve (24); and adjusting the driving frequency of the shut-off valve (24) so that the real opening time of the shut-off valve (24) is always over the lower limit value.